Electrochemical gas analyzers as well known in the art. Typical of the gas analyzers of the prior art are disclosed in my earlier granted U.S. Pat. Nos. 3,429,796; 3,767,552, and 4,077,861. These gas analyzers are utilized as sensors for determining the oxygen concentration in a gas mixture such as air. The electrochemical cell is defined with anode and cathode electrodes for producing an electrical output signal representative of the quantity of oxygen in the sensed gas mixture. The electrochemical cells of the prior art are further characterized as either galvanic cells or polarographic cells. The galvanic cell results from choosing appropriate active anode material such as lead for causing a reaction at the cathode electrode leading to the derivation of an output current from the cell. A polarographic electrochemical cell results from the selection of silver as an anode and applying a small polarizing potential between the cathode and anode electrodes to produce the cathodic reaction. The prior art electrochemical gas analyzers are generally satisfactory, although the leakage of electrolyte from the cell has always been a problem in the prior art type of analyzers. In addition, in the polarographic type of prior art cell wherein a silver anode electrode is employed in a potassium chloride electrolyte, a portion of the silver surface will oxidize and form silver chloride and thereby coat the electrode with the insoluble silver chloride. This coating on the anode electrode builds up to form an internal resistance that affects the accuracy of the output from the electrochemical cell. In the prior art it has been found necessary with these polarographic electrochemical cells to take the cell apart, when it works improperly, and scrub the silver electrode to eliminate the silver chloride coating, thus exposing the bright silver surface for reuse in the cell. Once this is done the cell is reassembled and it will operate satisfactorily. In addition to this physical scrubbing of the silver anode electrode, there is disclosed an electronic means for reactivating the cell by applying a reverse polarity pulse to the cell momentarily. This technique is disclosed in my U.S. Pat. No. 4,077,861. There is still a need in the art, however, for an improved electrochemical cell wherein the cell configuration allows it to be essentially maintenance free. In particular, the polarographic type of electrochemical cell requires that the cell be periodically reactivated and the elimination of this step is an important feature in rendering the cell maintenance free. In the case of sealed electrochemical cells, internal expansion due to both temperature effects and the diffusion of highly mobile background gases into the cell is a continuing problem. There is, therefore, a need to provide a cell that is totally unaffected by the relative diffusion rates of differing background gases. Also, a cell that is constructed without the need for expensive or intricate seals to avoid leaking of the electrolyte is desirable.